Storefront MCP and MCP well-known discovery

Usable counts stores whose /api/mcp server answers. Shopify moved cart and catalog tools to UCP, so those cart results count in the UCP row, not here.

MCP is a general protocol for agents to list and call tools. Many stores expose an MCP server. On Shopify, /api/mcp now serves the policy and FAQ tool, and catalog and cart moved to UCP at /api/ucp/mcp. Generic MCP discovery files under /.well-known are still emerging.

Governed by: Model Context Protocol: created at Anthropic, now an open project under the Linux Foundation. Storefront MCP is Shopify's per-store server at /api/mcp.

Official source: MCP specification · Shopify Storefront MCP

What ARC sees

Live: n = 3,309 stores with a completed HTTP check, latest as of 11 Oct 2026 (UTC). Live figures (n = 3,309) update hourly from saved checks. Downloads are the dated weekly snapshot 2026-10-09.r3, n = 3,308, so their counts can differ.

Declared

1519 / 330945.9%

Measured

/api/mcp answered a tools/list request with tools

Valid

1519 / 330945.9%

Measured

tools/list parsed with at least one named tool

Usable

1519 / 330945.9%

Measured

A tool or catalog answered on /api/mcp (on Shopify today, the policy and FAQ tool; or a catalog tool returned the tested product)

Transacts

—

Not measured

Of stores whose /api/mcp lists a cart tool, the cart tool returned a checkout link (stopped before payment). Not measured while no checked store lists one there.

What ARC checks

Lists tools on the store's /api/mcp endpoint.
Uses a storefront catalog or cart tool only when UCP does not offer one.
Shopify removed catalog and cart from /api/mcp in 2026 and serves them through UCP at /api/ucp/mcp. ARC counts those cart results in the UCP row, so MCP Transacts is not a sign that MCP fails.

What ARC can't check from outside

Generic /.well-known MCP discovery files: checked live on store pages but not saved, so not counted.
Private or authenticated MCP servers.

Methodology

Counts use each store's latest completed HTTP check saved by ARC. Failed checks are left out of the denominator. Each host counts once.

Measured means ARC observed it directly. Inferred means ARC links two observations that do not prove each other. Not measured means ARC has no saved evidence, and the count is not zero adoption.

A checkout link means a cart was created for one real product. It is not a completed purchase. ARC never places orders.

The sample is ARC's curated store list plus stores people checked. It is not all of e-commerce. Treat percentages as rates in this sample.

Reads make no store requests and no model calls.

Cite this

ARC Protocol Matrix: MCP, arcreport.ai/protocols/mcp, accessed 2026-10-11. Licensed CC-BY-4.0. Data: arcreport.ai/data.

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